The present embodiments relate to ultrasound imaging. In particular, the present embodiments relate to scanning with an electronically positioned aperture on an array.
An electronically rotated array is an array of elements where the aperture used during scanning is electronically controlled. Switches connect different elements to different beamformer channels, allowing rotation of the aperture for sequential scanning. For example, a one-dimensional aperture is rotated electronically on the face of a two-dimensional transducer array. By controlling the configuration of the switches, the one-dimensional array may be oriented to any rotational angle. Within a given aperture, the defined one-dimensional array may steer scan lines to ±45°, allowing an acoustic transmit and receive beam to be focused anywhere within a 90° cone extending out from the face of the transducer through scan line steering and aperture rotation. For volume scanning, the 90° cone in space is sampled by collecting a series of azimuth-spaced beam groups at each rotation angle.
One significant artifact caused by the sampling scheme described above in the presence of tissue motion is a large time gap in acquiring spatially adjacent rotation angle slices. If the scanning starts at the aperture rotation angle zero and then the remaining angle slices are acquired to complete a group of 60 scan planes with corresponding aperture locations, the first rotation angle at 0° is reconstructed adjacent in space to the angle slice with a rotation angle of 177°, even though they are acquired many transmit events apart in time. If there is significant motion, there may be a large discontinuity or “seam” in the reconstructed volume image.
To increase frame rate, data for additional scan lines may be interpolated from actual receive data. This analytic operation may be performed for scan lines in different apertures. Where a relatively large amount of time separates the acquisition between the two apertures, interpolation artifacts may be produced due to phase cancellation caused by motion.